Protective cap for writing instruments



Dec. 15, 1970 J. RsLr-:R

PROTECTIVE CAP FOR WRITING INSTRUMENTS 2 Sheets-Sheet 1 Filed Aug. 29, 1968 Dec. l5, 1970 1 J. RsLEl-Tv 3,547,552

RRoTEcTIvRv CAP RoR WRITING INsTRuMIxNTsV` Filed Aug. 29, 1968 2 sheets-sheet z Fig. .3. ffy. 2.

n IN VENTOR. JURCEN RsLER vUnited States Patent Inf. ci. Bsk 9/00 U.S. Cl. 401-243 8 Claims ABSTRACT OF THE DISCLOSURE For use in connection with a writing instrument having a shank with a pen comprising a writing point, a protectijve cap of a material with a relatively low heat coductivity, said cap having an internal layer of a material with a'high heat conductivity for substantially equalizing the temperature of said cap.

The present invention concerns a protective cap for the writing point of a writing instrument consisting of a non-metallic material and having a tightly sealed interior.

In the synthetic plastic caps that are nowadays widely used for writing instruments, water tends to condense. This condensate may eventually cause the formation of droplets which then Wet the front end of the writing instrument. The condensation of water principally occurs when the writing instrument is carried in a vertical position in an outer or inside jacket pocket since in this position the writing instrument becomes warm on the side adjacent the wearers body. Since plastics are poor conductors of heat and the air inside the sealed cap is humid, Water may condense on the colder side.

It is an object of the present invention to overcome the drawbacks set forth above.

It is another object of this invention to establish a good temperature equalization around the cap chamber to thereby avoid unilateral cooler or warmer areas.

These and other objects and advantages of the invention will appear more clearly from the following specification in connection with the accompanying drawing, in which:

FIG. 1 is an enlarged sectional representation of the front end of a fountain pen with a cap according to the invention, portions of the inner cap being shown broken away.

FIGS. 2 and 3 respectively illustrate two further modications.

In conformity with the present invention, itis proposed to provide in the interior of a cap for a writing instrument a substantially cylindrical metal liner which encloses the internal space, and which preferably consists of a metal that is a good conductor of heat, preferably a corrosion-resistant metal.

This metal liner operates to equalize the temperature in the enclosed interior of the cap and thus prevents one side of the interior from becoming colder than the other, causing the condensation of water.

If the cap of the writing instrument is a plain cap the metal liner may simply be bonded to the internal wall. However, if the cap is of the kind containing a supplementary inner cap which is adapted to create the seal, then the invention proposes to locate the metal liner between the outer and the inner caps. A particular useful arrangement consists in attaching the metal liner to the external surface of the inner cap in the form of a helically coiled thin ribbon. This arrangement has the incidental advantage that the metal liner can be formed from an inexpensive non-corrosion-resistant metal, such as aluminum.

3,547,552 Patented Dec. 15, 1970 ICC Referring now to the drawing in detail, the cap 2 fitted over the front end 1 of a fountain pen is a non-metallic external cap which may consist of a synthetic plastic or like material. The upper end of the cap 2 is closed by a screw-in head 3 which also grips the interposed retaining ring 40 of a clip 4, and which threadedly engages a cupshaped plug 5. The cup-shaped plug 5 axially movably locates a exible inner cap 6 which is adapted to make sealing contact with the external surface of the front end 1 of the body of the fountain pen. A coiled compression spring 7 which embraces the plug 5 and which is interposed lbetween a terminal flange on the inner cap 6 and an inside terminal fiange of the outer cap 2 serves to assist the formation of a tight seal inasmuch as it continuously urges that end of cap 6 which is remote from spring 7 into contact with the conically widening outer surface of pen 1.

For the purposes of the present invention it is irrevalent whether the inner cap 6 is alone responsible for ensuring a tight fit of the fountain pen cap or whether further connecting elements are provided between the outer cap 2 and the front end 1 of the body of the pen, such as a snap-action catch or a screw connection or an elastic inner ring.

As will be understood from the drawing, the outside of the inner cap 6 is cylindrically recessed, the recess containing a metal liner 8. This metal liner may be formed for instance by winding a thin aluminum ribbon around the recessed portion of the inner cap. In the present instance the inexpensive aluminum can be used although its corrosion resistance is low, because the metal liner does not come into contact with ink. Obviously the rigidity of the metal liner 8 must not be such as to impair the proper function of the inner cap 6, i.e. it must be sufficiently flexible to permit the inner cap to yield when the cap is fitted to the pen.

While in conformity with FIG. l, the metal liner 8 is connected to and located in a recess of an inner cap section 6, it is also possible to connect the metal liner 8 to the outer cap section 2 as shown in FIG. 2. According to still another modification illustrated in FIG. 3 in the inner cap section 6 is completely eliminated and the metal liner 8 is connected to the outer cap section 2 while a sealing section 9 of rubber or any other suitable material is arranged at the lower end of the metal liner 8 for engagement with the respective adjacent outer periphery of the front portion of a pen.

In this last mentioned instance the liner 8 may either be a metallic coating or inserted metal cylinder. Furthermore, with the embodiment of FIG. 3 the metal liner should preferably consist of a corrosion resistant material since it may come into direct contact with the ink, for instance, when the pen and the cap are fitted together with the pen held in a slanting position.

When the cap according to the invention was tested, it was found that the proposed arrangement reliably prevented the condensation of water and that the front end of the pen was never fouled nor did seepage of ink by capillary action ever occur.

It is understood, of course, that the present invention is not limited to the drawing and specification, but to the scope of the disclosure.

What I claim is:

1. For use in connection with a writing instrument having a shank with a pen comprising a writing point, a protective cap of a material with a relatively low heat conductivity, said cap having an internal layer of a matenial with a high heat conductivity for substantially equalizing the temperature of said cap, said cap including an outer cap section and an inner cap section arranged within said outer cap section and having a portion for substantially tight frictional engagement with the shank of a writing instrument, and said internal layer of high heat conductivity being interposed between said' outer and said inner cap sections.

2. A protective cap according to claim 1, in which said internal layer is a metal coating firmly bonded to the internal wall of the cap.

3. A protective cap according to claim 1, in which said outer cap section has an inwardly extending flange at one end thereof, and which includes: a holding member having a central threaded bore and being provided with a first shoulder near one end of said holding member and with a second shoulder near the opposite end of said holding member, clamping means including threaded bolt means engaging said threaded bore and detachably clamping said inwardly extending ange of said outer cap section against said first shoulder means, said inner cap section also having one end thereof provided with an inwardly extending, flange interposed between said second shoulder and the inwardly extending flange of said outer cap section, and spring means interposed between said flanges of said inner and outer cap sections and continuously urging the same away from each other.

4. A protective cap according to claim 1 in which said internal layer is attached to the outer surface of said inner cap section.

5. A protective cap according to claim 1, in which said internal layer is formed by a helically coiled metal ribbon.

6. A protective cap according to claim 1, in which said internal layer is aluminum.

7. A protective cap according to claim 1, in which the internal layer of a high heat conductivity is connected t0 the inner wall of said protective cap.

8. For use in connection with a writing instrument having a shank with a pen comprising a writing point, a protective cap of a material with a relatively `low heat conductivity, said cap having an internal layer of a material with a high heat conductivity for substantially equalizing the temperature of said cap, said cap including an outer cap section and an inner cap section arranged within said outer cap section and having a portion for substantially tight frictional engagement with the shank of a writing instrument, and said internal rlayer of high heat conductivity being connected to the inner wall of said outer cap section.

References Cited UNITED STATES PATENTS 704,262 7/1902 Lindsay 401-247 FOREIGN PATENTS 933,553 9/1955 Germany 401-244 LAWRENCE CHARLES, Primary Examiner 

